Coil for a slide fastener

ABSTRACT

A ZIPPER PLASTIC COIL FORMED AT ITS REARWARD END WITH A LINE OF KNOBS, ONE ON EACH CONVOLUTION, THE LINE BEING PARALLEL TO DIRECTION OF COIL FOR ENGAGING THE EDGE OF A TAPE IN AN &#34;INVISIBLE&#34; TYPE ZIPPER.

{kt 1971 J. E. BURBANK COIL FOR A SLIDE FASTENER Filed Aug. 21, 1970 INVENTO R John E.Burbank BYfiawb w- ATTORNEY United States Patent U.S. Cl. 24205.1 C 2 Claims ABSTRACT OF THE DISCLOSURE A zipper plastic coil is formed at its rearward end with a line of knobs, one on each convolution, the line being parallel to direction of coil for engaging the edge of a tape in an invisible type zipper.

This invention relates to a coil for a slide fastener. More specifically, this invention relates to a coil particularly adapted for use in the manufacture of so-called invisible zippers.

In the prior art, there are shown a number of plastic coil invisible zippers. As examples, the British Pat. 1,128,413, assigned to Lightening Fastener, and the French Pat. 1,529,317, assigned to Opti-Holding. Many of the prior art patents have required a grooving of the leg of each individual fastener element. Subsequently, the sewing thread engages in such a row of grooves, the idea being to hold the fastener elements firmly to the tape. An objection with prior art structures is that in grooving each fastener element there has resulted a weakening of the coil such that the coil has in the past broken under the unusual strain inherent in the structure of an invisible zipper.

The present invention involves the forming of the fastener elements to shape the fastener legs to enable them to be engaged by the tape and the stitching thread in a way which will assure maximum strength in the overall assembly. This avoids the grooving of the coil.

Further objects of the invention will be apparent to those skilled in the art from the following specification and the drawings all of which describe a non-limiting form of the invention. In the drawings;

FIG. 1 is a transverse sectional view of the engaged fastener elements in a typical invisible zipper embodying the present invention;

FIG. 2 is a front view of a coil embodying the invention;

FIG. 3 is a side view;

FIG. 4 is a rear view; and

FIG. 5 is a bottom view.

Referring more specifically to the drawings, an assembly of intermeshed stringers of an invisible zipper is generally designated in FIG. 1. It comprises a pair of tapes 12 which are doubled back as at 14 and to present a securing panel 16. As can be imagined, this structure leaves a simple, single, line between the two panels at the rearward bends 14 when viewed from the outside, hence the name invisible zipper. To the securing panels are secured the coil 18 by rows of stitches 20 secured to the respective tapes.

As shown in FIGS. 2 through 5, each coil comprises a number of identical convolutions 22 connected together to present a plurality of fastener elements.

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Each convolution comprises a pair of legs 24, 26. These legs are joined by a bight 28 which is enlarged upwards and downwards to form a head 30. As shown, one of the legs 26 is indented as at 32 inwardly closely adjacent the bight 28. Thereafter, the leg extends outwardly in a given direction. The other leg 24 extends directly from the bight 28 in the same direction but curves outward and upward as at 34 adjacent the heel or rear of the coil to form a lateral knob 36. At the end of leg 26, the filament angles down in a heel run 38 to the knob of the opposite leg 24 of the next adjacent fastener element.

Preferably as described, the major run portions of the two legs 24, 26 extend in the same direction. It should be understood that the deflection in each leg is for a specific purpose. In the case of leg 24, the deflection forming the knobs 36 provides in the finished coil a ledge against which the edge of the securing section '16 of the tape may abut to reduce the likelihood of the head section of the fastener elements pulling forwardly with respect to the tape. The deflection 32 on the leg 26 is formed to better be engaged by and prevent lateral slippage of the stitching threads.

The invention may be described in the following claim language:

I claim:

1. A coil for an invisible zipper comprising a series of identical convolutions of plastic filament each comprising a pair of legs, the legs being joined by a bight, the bight being upwardly and downwardly enlarged to form a head, one of said legs being indented adjacent the head and then extending outwardly in a first direction to its rearward end, the other leg extending directly back from the bight in said direction and adjacent its rearward end being curved outwardly and then presenting an upward stretch parallel to the direction of the coil to provide a tape-edge-engaging knob, the first-mentioned of said rearward ends having a heel run extending to the knob of the next adjacent convolution.

2. A coil for an invisible zipper comprising a series of identical convolutions of plastic filament each comprising a pair of legs, the legs being joined by a bight, the bight having an upward and downward enlargement to form a head, one of said legs having a straight run portion extending to its rearward end, the other leg extending directly back from the bight to provide a flat tape-engaging line and adjacent its rearward end being curved outwardly and then presenting an upward run parallel to the direction of the coil to provide a tape-edge-engaging knob, the first-mentioned of said rearward ends having a heel run extending to the knob of the next adjacent convolution.

References Cited UNITED STATES PATENTS 3,015,868 1/1962 Ruhrmann 24205.13 C 3,199,162 8/1965 Sohr 24205.13 C

BERNARD A. GELAK, Primary Examiner US. Cl. X.R. 24205.13 C 

